In December, the weather in Forte dei Marmi is typically cold. Average daily high temperature in December is about 7 degrees above zero. On average, Forte dei Marmi has 13 rainy, 9 sunny, 7 partly cloudy, and 2 cloudy days in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Forte dei Marmi.